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audio amp study

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Herschel:
I am making a single supply audio amp according to this circuit. even though the amp is biased by two diodes, here i used 1n4148 and a 22R resistor, why is this 200k potentiomete for? is it to control the output of the amp? not sure...
also the website dosent say anything about it.

https://www.eleccircuit.com/50-watt-audio-amplifier-circuit-with-pcb-using-2n3055/

MrAl:

--- Quote from: Herschel on April 19, 2024, 11:20:57 am ---I am making a single supply audio amp according to this circuit. even though the amp is biased by two diodes, here i used 1n4148 and a 22R resistor, why is this 200k potentiomete for? is it to control the output of the amp? not sure...
also the website dosent say anything about it.

https://www.eleccircuit.com/50-watt-audio-amplifier-circuit-with-pcb-using-2n3055/

--- End quote ---

Hi,

I did not look into this in depth but it looks like it could be for adjusting the crossover distortion.  That would control the quiescent current in the output transistors so that neither transistor could turn off completely even when the output signal polarity changes.

Herschel:
how am i supposed to adjest it? using a multimeter. is it possible to do that with a multimeter?

mariush:
Not gonna comment on that 200k resistor, but it would be much easier to just grab a couple TDA2050 amplifier chips, and make a stereo amplifier with them.

They're less than 60 cents on LCSC : https://www.lcsc.com/search?q=tda2050

You have example of single power supply circuit on page 6 in the datasheet : https://www.st.com/resource/en/datasheet/cd00000131.pdf

Or you could use a couple of them in bridge mode like in the TDA2030 example in this datasheet, on page 7 : https://www.lcsc.com/datasheet/lcsc_datasheet_2106070404_HGSEMI-TDA2030_C2683154.pdf

Or you could use 2 or 3 tda2050 amplifier chips, one for bass, one for mids and one for highs like in the tda2030 example on page 9 in the same datasheet above.dk52

Zenith:
Usually, the maker/designer specifies a quiescent current, which is a trade off between low distortion and low power consumption. You should be able to set it with a multimeter using their instructions.

You might contact the website and ask what they recommend.

Otherwise, in the absence of other test equipment, set it by ear. Try to find the lowest quiescent current that sounds acceptable.

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